1. Field of the Invention
Embodiments of the invention relate to a display device and a method of displaying an image.
2. Discussion of the Related Art
In general, a display device includes a display panel displaying an image and a driving circuit operating the display panel. The display panel has a plurality of pixels arranged in a matrix shape. A plurality of unit images produced by the plurality of pixels collectively display an image on the display device.
A viewing angle of the display device is measured with reference to a perpendicular line to the display panel. When a user views the display device beyond a specific viewing angle, an undesired abnormal image may be displayed. A display device has been suggested in which barriers are placed between a user and the display panel such that certain pixels can only be seen between the barriers depending on the viewing angle. In this type display device, displayed images are different according to viewing angles such that viewing zones are produced according to the different viewing angles. In other words, different pixels produce different viewing zones, and thus different images can be displayed in different viewing zones.
Such a barrier type display device can be used for a three-dimensional display device. The three-dimensional display device uses a principle of a stereo vision through both eyes. In other words, a parallax distance of both eyes, such as 65 mm, acts as a primary factor in the display of three-dimensional images. When the right and left eyes look at two respective two-dimensional images, the two two-dimensional images are transferred to the brain and then the brain mixes the two two-dimensional images so as to perceive them to be a three-dimensional image. Thus, realistic three-dimensional image having depth appears to be displayed.
Based upon the above principle of stereo vision through both eyes, a three-dimensional display device can be either a stereoscopic display device with glasses, a stereoscopic display device without glasses, or a holographic display device. The stereoscopic display device with glasses has disadvantages, such as inconvenience of wearing glasses and unnaturalness look due to viewing the display through glasses. The holographic display device has a difficulty in that large equipment is necessary for using a laser reference beam of display the image. However, the stereoscopic display device without glasses does not require glasses and has small equipment. The stereoscopic display devices without glasses are divided into a parallax barrier type, a lenticular type and an integral photography type. Of these types, presently, the parallax barrier type and the lenticular type have been typically used.
FIG. 1 is a view illustrating operation of a parallax barrier type display device according to the related art. Referring to FIG. 1, the parallax barrier type display device 10 includes a display panel 20 simultaneously displaying a left-eye image and a right-eye image, and a parallax barrier 30. A left-eye pixel L and a right-eye pixel R are alternately arranged in the display panel 20. The parallax barrier 30 is disposed between the display panel 20 and a user 40. The parallax barrier 30 has a slit 32 and a barrier 34 by which light emitted from the left-eye and right-eye pixels L and R selectively passes through the parallax barrier 30. The slit 32 and the barrier 34 are alternately arranged in a vertical direction with respect to the user 40.
A left-eye image IL produced by the left-eye pixel L passes through the slit 32 and reaches a left eye of the user 40, and a right-eye image IR produced by the right-eye pixel R passes through the slit 32 and reaches a right eye of the user 40. The left-eye and right-eye images IL and IR see separate images in parallax, and the user 40 combines the two images to perceive a three-dimensional image.
A width P of each of the left-eye and right-eye pixels L to R, a width P1 of the slit 32, a width P2 of the barrier 34, and an interval E, such as 65 mm, between the left and right eyes are expressed as the following relation expression.P1+P2=2/(1/E+1/P)  {1}By adjusting the width P of the left-eye and right-eye pixels L to R, the width P1 of the slit 32 and the width P2 of the barrier 34 in consideration of the interval E between the left and right eyes, the display device 10 can display a desired three-dimensional image.
FIG. 2 is a view illustrating operation of a lenticular type display device according to the related art. Referring to FIG. 2, the lenticular type display device 15 includes a display panel 20 simultaneously displaying a left-eye image and a right-eye image, and a lenticular array 50. A left-eye pixel L and a right-eye pixel R are alternately arranged in the display panel 20. The lenticular array 50 is disposed between the display panel 20 and a user 40. The lenticular array 50 has lenticular lens 52 by which lights emitted from the left-eye and right-eye pixels L and R selectively are refracted. The lenticular lens 52 has a semi-cylindrical shape in a vertical direction with respect to the user 40.
A left-eye image IL produced by the left-eye pixel L is refracted by the lenticular lens 52 and reaches a left eye of the user 40, and a right-eye image IR produced by the right-eye pixel R is refracted by the lenticular lens 52 and reaches a right eye of the user 40. The left-eye and right-eye images IL and IR include separate images considering a parallax, and the user 40 combines the two images to perceive a three-dimensional image. By adjusting a width P of the left-eye and right-eye pixels L to R and a width and a spherical surface radius of the lenticular lens 52 in consideration of the interval E between the left and right eyes, the display device 15 can display the three-dimensional image desired.
Users desire to see large images. As explained above, the related art parallax barrier type or lenticular type display device produce two viewing zones using the parallax barrier or the lenticular array to display a perceived three-dimensional image. However, size of the image displayed in these types of devices is limited to the size of the display panel.